Robust control/estimator design by frequency-shaped cost functionals

Frequency-shaping methods developed for control law design are extended for robust state estimation and for robust feedback control when a filter is used for state estimation. Robustness is achieved by reducing filter gain outside model bandwidth. The frequency-shaping of cost functionals can also be used to design several low-order controllers for a high-order system. A complete design algorithm has been developed. Physical knowledge of the system as well as estimation requirements can be incoprorated in the estimator. A highly robust control system can be obtained when a frequency-shaped estimator is used in feedback design.